Historically, influenza* was ascribed to a number of different agents, including "bad air" and several different bacteria. It wasn't until 1933 that the causative agent was finally identified as a virus.

As anyone who has ever suffered the flu can attest, common symptoms* include a combination of headache, dry cough, fever and achiness, nasal congestion and even a sore throat. The National Institute of Health has written an article, "Cold, flu, or allergy? Figuring out what's ailing you," to assist people in making sense of their symptoms.

There are many strains of the influenza virus, most of which are of little concern to a majority of the population. However, there are a few strains that have caught more than their fair share of notice in recent months. Here we offer background information and prevention techniques for seasonal, H1N1 and H5N1 flu strands.

Seasonal Flu

Flu.gov, a government website devoted to providing accurate and updated flu information, defines seasonal flu as influenza viruses that follow predictable seasonal patterns. Due to repeated exposure many people are able to develop a strengthened immunity to these strands. The flu season generally runs from October until April each year, although exceptions can exist. Vaccines are often available at the beginning of an outbreak due to the predictable nature of this virus making it easier to prevent. Healthy adults are usually not at risk for serious complications. The impact that this strand of flu has on society is often modest.

Prevention: The Springfield-Greene County Health Department has produced an informative pamphlet on seasonal influenza [pdf]. In this pamphlet they recommend an annual flu shot as the surest means to prevent contracting the flu virus. You can also protect yourself and others by practicing good health habits like frequent hand washing with soap and water, covering your mouth and nose with a tissue when you cough or sneeze and avoiding contact with people who are sick. The Springfield-Greene County Health Department began administering flu shots to high risk individuals on October 5, 2009. Visit their website for more information.

H1N1 (Swine Flu)

The H1N1 flu virus is often referred to as "swine flu," which is a misnomer. When this flu strain was first discovered it was thought to be similar to a flu virus that is commonly found in pigs. Further study has shown that H1N1 is not the same as the strand that circulates in North American pigs.

H1N1 spreads the same as the seasonal flu, through exposure to the coughing or sneezing of a person who has the virus. Illness has ranged from mild to severe, with the Centers for Disease Control (CDC) reporting that while hospitalizations and death occur most people recover without the need for medical treatment. On June 11, 2009, the World Health Organization (WHO) signaled that a pandemic of 2009 H1N1 flu was underway. The Springfield-Greene County Health Department defines a pandemic as a global disease outbreak that occurs when a new strain of influenza virus emerges to which people have little or no immunity. Because people have no immunity the virus is easily passed from person-to-person and travels quickly around the world, causing illness and death.

Prevention: Basic preventitive techniques include frequent hand washing with soap and water, covering your mouth and nose with a tissue when you cough or sneeze and avoiding contact with people who are sick. The seasonal flu vaccine is not expected to protect against the 2009 H1N1 flu. The first shipment of the H1N1 vaccine arrived in the Ozarks on October 5, although it still remains in short supply. CoxHealth is asking patients to contact their primary care physician to be placed on a waiting list for the vaccine.

H5N1 (Avian Flu)

H5N1 is an influenza strand that is common among birds, hence the common name of "avian flu." This flu is not strictly restricted to birds, however. It has been found that humans can contract this virus, as well. The CDC reports that most of these cases have resulted from people having direct or close contact with H5N1-infected poultry or H5N1-contaminated surfaces. While there has been some human-to-human spread of H5N1, it has been limited.

This strain also differs from the seasonal flu in that its spread is unpredictable and most people don't have a strong immunity. The CDC has determined that if H5N1 virus were to gain the capacity to spread easily from person to person an influenza pandemic (worldwide outbreak of disease) could begin. However, this virus is not considered to be pandemic at this time. The WHO has developed the Influenza Virus Tracking System to assist in monitoring H5N1 as well as other potentially pandemic subtypes.

Prevention: Unlike the seasonal flu or H1N1, the H5N1 virus is not easily transmitted from person to person. The Springfield-Greene County Health Department recommends good handwashing as a preventative measure for this virus. They note that scientists do not believe that H5N1 is transmitted from eating infected poultry or eggs; however, to protect yourself from food-borne and other illnesses, always store and handle uncooked meat safely, wash your hands before and after handling meat and cook it to a safe internal temperature.

A vaccine for H5N1 has recently been approved for use in the United States. However, it will still require several years of testing before it is available on the market. The seasonal influenza vaccination does not offer protection against the H5N1 influenza strand.